Inductors and transformers may be used in many different types of circuits. For example, they may be used for radio frequency (RF) circuits and high-frequency power distribution or conversion systems, such as a DC-DC voltage (or power) converter. Currently voltage converters may not be fully integrated on-chip for a variety of reasons. For example, a desired operating frequency may require an inductance value that is unobtainable based on the constrained physical size of the inductor or transformer. Further, in particular based on the effects of eddy currents, an on-chip inductor or transformer may not have a sufficiently high operating frequency for an RF or high-frequency voltage conversion application.
There are advantages to integrating a power system, for example including a DC-DC voltage converter, on the same die as the circuit(s) that are powered thereby. For example, as processor technology scales to smaller dimensions, supply voltages to circuits within a processor may also scale to smaller values. However, as the dimensions decrease, power consumption of the processor may increase. Using an off-die voltage converter to provide a small supply voltage to a processor with a large power consumption leads to a large total electrical current being supplied to the processor. This may increase the electrical current per pin, or the total number of pins required to power the processor as each pin has a maximum current handling capability. Also, an increase in supply current can lead to an increase in resistive as well as inductive voltage drop across various off-die and on-die interconnects, and to a higher cost for decoupling capacitors. Integrating the voltage converter onto the die may mitigate these and other problems.